After a building's framing has been completed, electrical boxes to accommodate the building's electrical outlets, switches, light fixtures and other wiring devices are attached to the wood or metal studs. These boxes must be located at predetermined distances from the floor. The boxes must also be mounted to extend outwardly at the front surface of the studs at a distance to accommodate the thickness of the finished wall materials.
The electrician or electrician's helper typically relies on only the most basic tools for the task of installing electrical boxes on the framing components of a building. These basic tools consist of such things as a hammer and tape measure. Each time an electrical outlet or switch box is installed, two separate measurements must be made. First, the distance from the floor must either be independently measured then marked on the stud or established using a stick marked at the proper heights for the various boxes. Second, the distance by which the box must extend beyond the face of the stud is determined. To save time, this depth measurement may just be estimated, sometimes with the help of some depth markings along the outside face of the junction box. This practice often results in boxes that do not protrude far enough or, worse, protrude too far from the surface of the studs. In addition, if a box is not held securely while fastening, it can be set at an angle to the surface of the stud. Any of these conditions result in difficulties during the finish stage of the project.
A typical residential building can use hundreds of electrical boxes for outlets, switches, TV cable, telephone, intercoms, etc. Typical commercial structures require even greater quantities of electrical boxes. After installing several dozen boxes, especially those which are mounted near to the floor level, the worker can experience fatigue and back pain. If the worker is not highly skilled, or if he or she is pressured to work too quickly, boxes may be poorly aligned to the framing, and mounting heights from the floor may not be consistent. This frequently results in later difficulties and quality problems when the finish work is completed (installation of receptacles and switches, etc.).
Many electricians, apprentices and helpers would find it very beneficial, therefore, to have a tool that helps in installing electrical boxes at the proper height, depth, and alignment without the need for repeated measuring, bending or kneeling.
Several devices have been designed to hold electrical boxes at the proper depth from and alignment to the surface of the upright stud. These devices have a number of limitations and disadvantages that are not present in the applicants' invention. For example, the devices disclosed in the relevant art will not securely hold the wide variety of electrical box sizes and shapes currently in use. Boxes are now available in varying widths, with two, three and even four-gang boxes not uncommon. Rectangular, square, hexagonal and partially circular shapes are typical. These devices cannot be used with the many electrical boxes having protuberances on their inside walls for grounding straps, multi-size fixture mounting structures and the like. These devices do not allow for the installation of boxes on multiple stud widths typically found in light switch boxes adjacent to doorways. A further limitation of the devices disclosed in the relevant art is the inability to install boxes at varying depths relative to the surface of the stud without exchanging or adding components to the device. With a few exceptions, these devices do not eliminate the need for repeated bending or kneeling to install the lower mount boxes.
Insofar as applicants are aware, the most relevant art is illustrated in U.S. Pat. No. 4,850,115 (Price et al.). The Price device allows installation of electrical boxes at a range of elevations, but at only one depth setting without removing and exchanging parts. The Price device is further limited in the range of height settings by the overall length of the device's "tubular support member" which is stated to be five (5) feet long in an actual embodiment. The Price device relies on a U-shaped spring as a gripping means which contacts only a very small percentage of the surface area of the box. This gripping means cannot securely grip a box of larger than single-gang size, especially if these larger boxes are made of steel or some other relatively heavy substance.
Some attempts have been made to more securely grip the box, such as the internal expansion bands used in the device shown in U.S. Pat. No. 4,888,879 (Dixon). The internal expansion bands of Dixon function with electrical boxes of only one width (single-gang). In U.S. Pat. No. 4,181,295 (Duffy), an increased gripping surface area was added by including a thin steel blade which slides between the box and the side of the stud. The Duffy device must be withdrawn before the box is securely fastened to the stud. Failure to withdraw this device at the proper instant would result in its being lodged in place between the box and the stud.
In U.S. Pat. No. 4,479,639 (Kane), an attempt was made to accommodate protuberances on the inside walls of electrical boxes. The Kane device, however, functions with a very limited size and configuration of an internal appurtenance which is typical only on an obsolete round fixture box design. The Kane device continues to rely on at least one gripping surface contacting the internal walls of the box. Modern plastic fixture boxes include many variations on internal design which the Kane device does not address.